1. Technical Field
The present disclosure relates to audio devices, and more particularly to volume adjusting circuit for the audio devices.
2. Description of related art
Audio devices, such as CD/DVD players, MP3 (MPEG-1 audio layer III) players, and MP4 (MPEG-4) players are widely used. A typical audio device generally has an internal speaker and an earphone plug detachably connecting with a jack. Thus, the audio device can selectively output sound to the internal speaker or to the earphones that is external to the audio device.
Normally, volume of a speaker is much higher than that of an earphone due to the sizes thereof. Therefore, when the internal speaker is selected to output sound, the volume of the audio device needs to be high. On the other hand, when the earphone is selected as an output, the volume of the audio device needs to low. The volume of the audio device needs to, accordingly, be adjusted. A conventional method for adjusting the volume consults a list of predetermined volume levels. Each volume level has a gain indicating an adjustable volume range. However, the suitable volume levels for the internal speaker and the external earphone are different. It is inconvenient for users to adjust the volume of the other sound producer to a perfect value.
Therefore, it is desirable to provide an audio device and a volume circuit thereof overcoming the described shortcomings and deficiencies.